Our current 13 week, high intensity, laboratory-based balance and/or strength training intervention trial has produced a meaningful and sustained (6 month post-intervention) improvement in balance and strength in a study using 110 healthy subjects with an average age of 79 years. As the next step in the development of a balance and strength intervention geared towards improving functional status with the potential for widespread use, we propose a community-center based trial using small groups which is directed at frail and near frail persons 70 years and above. We have recently completed a pilot study of 50 subjects which demonstrated feasibility of identifying and recruiting older persons with decreased functional performance, safety and efficacy of the intervention and sensitivity and reliability of primary outcome measures. We propose to enroll 142 subjects into an intervention trial which will target specific components of mobility for training. These are: mechanical performance (muscle force and flexibility), neurologic control (balance, eccentric muscle control), and fitness (endurance). We will first examine the effect of a 3-month strength, flexibility and endurance (SFE) program on performance and function, and then evaluate the effect of 3 months of balance and functional training, while continuing with endurance component (BFE). The augmented physical performance realized from SFE serves as the foundation for the 2nd, more complex, 3 month phase (BFE), which emphasizes training in mobility, balance and functional activities (e.g. walking and stair climbing). Maintenance of improved physical capability will be achieved with a follow-up exercise program over the next 12 months. The primary outcome will be determined in terms of the effects on physical performance tests at baseline, 3, 6, 12 and 18 months and after completion of the intervention. Outcome will also be determined in terms of the effect on quantitative measures of balance and strength. A secondary aim of the study is to develop a laboratory measure of dynamic balance which will advance our understanding of the contribution of balance to changes in physical performance.